1、 ISO 2016 Metallic materials Unified method of test for the determination of quasistatic fracture toughness Matriaux mtalliques Mthode unifie dessai pour la dtermination de la tnacit quasi statique INTERNATIONAL STANDARD ISO 12135 Second edition 2016-11-15 Reference number ISO 12135:2016(E) ISO 1213
2、5:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
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4、11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 12135:2016(E)Foreword v 1 Scope . 1 2 Normative references 1 3 Terms and definitions . 1 4 Symbols and designations 2 5 General requirements . 5 5.1 General . 5 5.2 Fracture parameters. 7 5.3 Fracture toughness symbols . 8 5.4 Test specimens 8
5、 5.4.1 Specimen configuration and size . 8 5.4.2 Specimen preparation 12 5.5 Pre-test requirements 18 5.5.1 Pre-test measurements .18 5.5.2 Crack shape/length requirements .19 5.6 Test apparatus 19 5.6.1 Calibration 19 5.6.2 Force application 19 5.6.3 Displacement measurement .19 5.6.4 Test fixtures
6、 .20 5.7 Test requirements .24 5.7.1 Three-point bend testing .24 5.7.2 Compact tension testing .24 5.7.3 Specimen test temperature24 5.7.4 Recording 25 5.7.5 Testing rates 25 5.7.6 Test analyses .25 5.8 Post-test crack measurements .25 5.8.1 General.25 5.8.2 Initial crack length, a o.25 5.8.3 Stabl
7、e crack extension, a .28 5.8.4 Unstable crack extension .28 6 Determination of fracture toughness for stable and unstable crack extension 29 6.1 General 29 6.2 Determination of plane strain fracture toughness, K lc.30 6.2.1 General.30 6.2.2 Interpretation of the test record for F Q30 6.2.3 Calculati
8、on of K Q31 6.2.4 Qualification of K Qas K lc.32 6.3 Determination of fracture toughness in terms of .32 6.3.1 Determination of F cand V c , F uand V u , or F ucand V uc.32 6.3.2 Determination of F mand V m.34 6.3.3 Determination of V p34 6.3.4 Calculation of .34 6.3.5 Qualification of fracture toug
9、hness value .35 6.4 Determination of fracture toughness in terms of J 35 6.4.1 Determination of F cand q c , F uand q u , or F ucand q uc35 6.4.2 Determination of F mand q m36 6.4.3 Determination of U p36 6.4.4 Calculation of J o37 6.4.5 Qualification of J ofracture toughness value 37 ISO 2016 All r
10、ights reserved iii Contents Page ISO 12135:2016(E)7 Determination of resistance curves J -a and J-a and initiation toughness J0,2BLand J 0,2BLand Jiand J ifor stable crack extension .38 7.1 General 38 7.2 Test procedure 38 7.2.1 General.38 7.2.2 Multiple-specimen procedure .38 7.2.3 Single-specimen
11、procedure .38 7.2.4 Final crack front straightness 38 7.3 Calculation of J and J39 7.3.1 Calculation of J .39 7.3.2 Calculation of J39 7.4 R-curve plot .40 7.4.1 Plot construction 41 7.4.2 Data spacing and curve fitting .42 7.5 Qualification of resistance curves 42 7.5.1 Qualification of J-a resista
12、nce curves .42 7.5.2 Qualification of J a resistance curves 43 7.6 Determination and qualification of J 0,2BLand J0,2BL44 7.6.1 Determination of J 0,2BL.44 7.6.2 Determination of J0,2BL45 7.7 Determination of initiation toughness J iand Jiby scanning electron microscopy (SEM) 46 8 Test report 46 8.1
13、 Organization .46 8.2 Specimen, material and test environment .47 8.2.1 Specimen description .47 8.2.2 Specimen dimensions .47 8.2.3 Material description . 47 8.2.4 Additional dimensions .47 8.2.5 Test environment .47 8.2.6 Fatigue precracking conditions 47 8.3 Test data qualification .48 8.3.1 Limi
14、tations .48 8.3.2 Crack length measurements .48 8.3.3 Fracture surface appearance 48 8.3.4 Pop-in .48 8.3.5 Resistance curves .48 8.3.6 Checklist for data qualification .48 8.4 Qualification of K lc.49 8.5 Qualification of the J -R Curve 49 8.6 Qualification of the J-R Curve .50 8.7 Qualification of
15、 J0,2BL(B)as J0,2BL.50 8.8 Qualification of J 0,2BL(B)as J 0,2BL.50 Annex A (informative) Determination of Jiand J i.51 Annex B (normative) Crack plane orientation 56 Annex C (informative) Example test reports .57 Annex D (normative) Stress intensity factor coefficients and compliance relationships
16、66 Annex E (informative) Measurement of load-line displacement q in the three-point bend test 71 Annex F (informative) Derivation of pop-in formulae 76 Annex G (informative) Analytical methods for the determination of V pand U p.78 Annex H (informative) Guidelines for single-specimen methods .80 Ann
17、ex I (normative) Power-law fits to crack extension data (see Reference 42) 95 Bibliography .96 iv ISO 2016 All rights reserved ISO 12135:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of p
18、reparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental,
19、in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/
20、IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibilit
21、y that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of pate
22、nt declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformit y assessment, as well as inf
23、ormation about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html. The committee responsible for this document is ISO/TC 164, Mechanical testing of metals, Subcommittee SC 4, Toughness testing
24、Fracture (F), Pendulum (P), Tear (T). This second edition cancels and replaces the first edition (ISO 12135:2002), which has been technically revised. It also incorporates the Technical Corrigendum ISO 12135:2002/Cor 1:2008. ISO 2016 All rights reserved v Metallic materials Unified method of test fo
25、r the determination of quasistatic fracture toughness 1 Scope This document specifies methods for determining fracture toughness in terms of K, , J and R-curves for homogeneous metallic materials subjected to quasistatic loading. Specimens are notched, precracked by fatigue and tested under slowly i
26、ncreasing displacement. The fracture toughness is determined for individual specimens at or after the onset of ductile crack extension or at the onset of ductile crack instability or unstable crack extension. In some cases in the testing of ferritic materials, unstable crack extension can occur by c
27、leavage or ductile crack initiation and growth, interrupted by cleavage extension. The fracture toughness at crack arrest is not covered by this document. In cases where cracks grow in a stable manner under ductile tearing conditions, a resistance curve describing fracture toughness as a function of
28、 crack extension is measured. In most cases, statistical variability of the results is modest and reporting the average of three or more test results is acceptable. In cases of cleavage fracture of ferritic materials in the ductile-to-brittle transition region, variability can be large and additiona
29、l tests may be required to quantify statistical variability. Special testing requirements and analysis procedures are necessary when testing weldments and these are described in ISO 15653 which is complementary to this document. When fracture occurs by cleavage or when cleavage is preceded by limite
30、d ductile crack extension, it may be useful to establish the reference temperature for the material by conducting testing and analysis in accordance with ASTM E1921. 2 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitut
31、es requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3785, Metallic materials Designation of test specimen axes in relation to product texture ISO 7500-1,
32、Metallic materials Calibration and verification of static uniaxial testing machines Part 1: Tension/compression testing machines Calibration and verification of the force-measuring system ISO 9513, Metallic materials Calibration of extensometer systems used in uniaxial testing 3 Terms and definition
33、s For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/ /www.electropedia.org/ ISO Online browsing platform: available at http:/ /www.iso
34、.org/obp 3.1 stress intensity factor K magnitude of the elastic stress-field singularity for a homogeneous, linear-elastic body Note 1 to entry: The stress intensity factor is a function of applied force, crack length, specimen size and specimen geometry. INTERNATIONAL ST ANDARD ISO 12135:2016(E) IS
35、O 2016 All rights reserved 1 ISO 12135:2016(E) 3.2 crack-tip opening displacement relative displacement of the crack surfaces normal to the original (undeformed) crack plane at the tip of the fatigue precrack, evaluated using the rotation point formula 3.3 crack-tip opening displacement Jestimate of
36、 the crack-tip opening displacement, obtained from J 3.4 J-integral line or surface integral that encloses the crack front from one crack surface to the other and characterizes the local stress-strain field at the crack tip 3.5 J loading parameter, equivalent to the J-integral, specific values of wh
37、ich, experimentally determined by this method of test (J c , J i , J u ,), characterize fracture toughness under elastic-plastic conditions 3.6 stable crack extension crack extension which stops or would stop when the applied displacement is held constant as a test progresses under displacement cont
38、rol 3.7 unstable crack extension abrupt crack extension occurring with or without prior stable crack extension 3.8 pop-in abrupt discontinuity in the force versus displacement record, featured as a sudden increase in displacement and, generally, a decrease in force followed by an increase in force N
39、ote 1 to entry: Displacement and force subsequently increase beyond their values at pop-in. Note 2 to entry: When conducting tests by this method, pop-ins may result from unstable crack extension in the plane of the precrack and are to be distinguished from discontinuity indications arising from: i)
40、 delaminations or splits normal to the precrack plane; ii) roller or pin slippage in bend or compact specimen load trains, respectively; iii) improper seating of displacement gauges in knife edges; iv) ice cracking in low-temperature testing; v) electrical interference in the instrument circuitry of
41、 force and displacement measuring and recording devices. 3.9 crack extension resistance curves R-curves variation in Jor J with stable crack extension 4 Symbols and designations See Table 1.2 ISO 2016 All rights reserved ISO 12135:2016(E) Table 1 Symbols and their designations Symbol Unit Designatio
42、n a mm Nominal crack length (for the purposes of fatigue precracking, an assigned value less than a o ) a f mm Final crack length (a o+ a) a i mm Instantaneous crack length a m mm Length of machined notch a o mm Initial crack length A p J Plastic component of the area under the force vs. notch openi
43、ng displacement diagram (Figure 17) a mm Stable crack extension including blunting a max mm Crack extension limit for or J controlled crack extension B mm Specimen thickness B N mm Specimen net thickness between side grooves C m/N Specimen elastic compliance E GPa Modulus of elasticity at the pertin
44、ent temperature F kN Applied force F c kN Applied force at the onset of unstable crack extension or pop-in when a is less than 0,2 mm offset from the construction line (Figure 2) F d kN Force value corresponding to the intersection of the test record with the secant line (Figure 16) F f kN Maximum f
45、atigue precracking force F m kN Maximum force for a test which exhibits a maximum force plateau preceding fracture with no significant prior pop-ins (Figure 2) F Q kN Provisional force value used for the calculation of K Q F u kN Applied force at the onset of unstable crack extension or pop-in when
46、a is equal to or greater than than 0,2 mm offset from the construction line (Figure 2) J MJ/m 2 Experimental equivalent to the J-integral J c(B) MJ/m 2 Size sensitive fracture resistance J at onset of unstable crack extension or pop-in when stable crack extension is less than 0,2 mm offset from the
47、construction line (B = speci- men thickness in mm) J g MJ/m 2 J at upper limit of J-controlled crack extension J i MJ/m 2 Size-insensitive fracture resistance J at initiation of stable crack extension J m(B) MJ/m 2 Size sensitive fracture resistance J at the first attainment of a maximum force plate
48、au for fully plastic behaviour (B = specimen thickness in mm) J max MJ/m 2 Limit of J-R material behaviour defined by this method of test J u(B) MJ/m 2 Size sensitive fracture resistance J at the onset of unstable crack extension or pop-in when the event is preceded by stable crack extension equal t
49、o or greater than 0,2 mm offset from the construction line (B = specimen thickness in mm) J uc(B) MJ/m 2 Size sensitive fracture resistance J at the onset of unstable crack extension or pop-in when stable crack extension cannot be measured (B = specimen thickness in mm) J o MJ/m 2 J uncorrected for stable crack extension J 0,2BL MJ/m 2 Size insensitive fracture resistance J at 0,2 mm stable crack extension offset from the construction line J 0,2BL(B) MJ/m 2 Size sensitive fr
